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The carbon emission is not a problem, the imbalance is. When we burn fossil fuels, we use carbon that was stored by dead plants being buried. We take carbon fro

The carbon emission is not a problem, the imbalance is. When we burn fossil fuels, we use carbon that was stored by dead plants being buried. We take carbon from the ground and dump it in the atmosphere. Plants take carbon from the atmosphere. If were to bury the equivalent amount of wood, we would be equal. Buried wood is not useful, but building from it also locks the carbon somewhere else that isn't an atmosphere. So... there actually is a finite number of wooden airports that completely offsets airplane carbon emissions.

katangafor 2y ago
Does burying wood actually work? I'm assuming it's a little more complicated than literally burying it, cause wouldn't it decay and release carbon at some point anyway?
- devilbunny 2y ago
  Without oxygen, any decay is going to be incredibly slow. They're still pulling usable timber from trees that sank in rivers after being cut in the southeastern US 200 years ago. It's not cheap, but if you want some real old-growth oak, it's a viable source. And that's not a completely anaerobic environment.
  - williamdclt 2y ago
    200y is not really an incredibly long time at all
    - devilbunny 2y ago
      No, it's not, but that's without any noticeable decay. A tree that's been felled in that environment and left above ground will rot very quickly.
- Arrath 2y ago
  As most of the heavy construction and earth moving equipment you'd use to bury the wood will be burning diesel and releasing carbon the entire time, you enter some new Tyranny of the Rocket/Wagon equation.
ericd 2y ago
There's a simple way to think about this that doesn't require doing a ton of research and number crunching. Think about the volume of fuel in a single airplane, about 7,000 gallons for a 737, or about 100 55 gallon drums. It's nowhere near exact, but you can roughly equate that volume of fuel to the volume of volume of wood to compare carbon - I'm pretty sure this is being very generous to the energy density of the wood, but it gives you an upper limit on what the wood could be sequestering (I think in reality jet fuel is something like 2-3x as energy/carbon dense per m^3). Now think about how many planes take off every day from an airport, and the volume of n*100 drums. It's just nowhere near in reality, and we're not going to make a large dent via sequestration, the "finite" airports is functionally infinite for our purposes. We have to start making carbon neutral fuel. That said, manufacturing concrete is incredibly carbon intensive, so avoiding making the amount we would've needed for this building is a pretty good win.
burkaman 2y ago
> If were to bury the equivalent amount of wood, we would be equal. Burying wood that would have taken decades to decay is not equal to instantly releasing the equivalent amount of carbon. I'm not sure it's physically possible to remove CO2 from the atmosphere at the same rate a plane emits it, which would be the only way to genuinely "offset" the emissions.
closewith 2y ago
1 kilo of wood sequesters (temporarily for the most part) about 2kg CO2 equivalent, so for the GP's example of a single seat one-way from Boston - NYC, you'd need to sequester 350kg of wood. To sequester the ~800 Mt of CO2 emitted by aviation annually, you'd need to sequester about 400 billion kilograms of wood. So a finite but absurd amount.
- LargeWu 2y ago
  Not only that, you have to build new wooden airports every single year to keep up.
- kjkjadksj 2y ago
  Or you transition the airline industry to biofuels that are inherently carbon neutral.
pmayrgundter 2y ago
Interesting point! It looks like Skanska is GC for the Project, and cites it as a 9 acre (!) lumber roofing system[SK], and that it uses 3.5M board foot of Douglas Fir Project Lumber[PL]. Douglas Fir is 3.2 pounds per board foot, or 1.45kg [DFM]. So 1.45 * 3.5M = 5Mkg of lumber for PDX airport. DF has an Embodied CO2 of 1.6kgCO2/kgLumber [DFC]. A little hard to believe? But maybe that's bc a lot of the mass of a tree is left in the ground. Worth following up. 1.6kgCO2/kgLumber * 5MkgLumber = 8MkgCO2 = 8KtCO2 embodiment/sequestration from the PDX roof project. (tho there's a lot more to the project that probably goes in the other direction) Global CO2 emissions from commercial flights is ~60MtCO2/month [CF], so we need roughly 12,000 airports per month, 144,000/yr, to offset flight CO2 emissions. There's 9000 commercial airline airports [NA] (tho obv many smaller than PDX, but they would also represent less CO2 from their flights), so 144,000/9000 is a 16x annual airport rebuild rate we'd need to offset CO2 emissions from the flights they service. So yeah, this is absurd on the face of it. But, how much of the mass of an airport is the roof? If it's like 1/100th the total mass, and you start building airports with all wood (foundation, runways, etc) you'd get to 16% annual rebuild rate to offset flight emissions. Still too high to be plausible. But another 10x somehow and you get to ~1% range of annual airport rebuild rate to offset emissions. Then you'd have something. [SK] https://www.usa.skanska.com/what-we-deliver/projects/278172/Portland-International-Airport-PDX-Terminal-Core-Redevelopment https://www.usa.skanska.com/what-we-deliver/projects/278172/... [PL] https://www.forbes.com/sites/johnoseid/2024/08/19/portlands-pdx-airport-dazzles-with-its-new-timber-roof-terminal/ https://www.forbes.com/sites/johnoseid/2024/08/19/portlands-... [DFM] https://www.globalwood.org/tech/tech_wood_weights.htm https://www.globalwood.org/tech/tech_wood_weights.htm [DFC] https://www.douglasfir.co.nz/net/environment/carbon-footprint.aspx https://www.douglasfir.co.nz/net/environment/carbon-footprin... [CF] https://www.statista.com/statistics/1500409/global-aviation-co2-emissions-by-month https://www.statista.com/statistics/1500409/global-aviation-... [NA] https://sentinel-aviation.com/blog/over-40000-airports-in-the-world-only-9000-served-by-commercial-airlines https://sentinel-aviation.com/blog/over-40000-airports-in-th...
- pmayrgundter 2y ago
  Based on the discussion in the descendent thread with morsch, it seems like the runways are the real story, at 1000x the mass of the airport roof. But concrete is not so CO2 intensive. Lumber has a +1.6 sequestration factor of CO2 emitted vs built mass, compared with concrete at -0.8. So we'd need runways made mostly of wood, or combined with a Woodcrete that was net sequestering, and then maybe there's a way to make even our most CO2 intensive industries net neutral so long as we rebuild continuously. Also, since construction is about 40% of global CO2 emissions, if it could become a net sequestration as a whole, maybe it could flip the sign to -40% and offset most of the rest of our industrial emissions. This also got me interested in what's a good number for rebuild rate. Found a study that concludes the "Apparent ecosystem carbon turnover time [T]" is 43±7 years. So maybe we should be rebuilding our built environment at 2.3%, or probably higher since species have evolved to be more energy intensive, humans especially. [T] https://essd.copernicus.org/articles/12/2517/2020/essd-12-2517-2020.pdf https://essd.copernicus.org/articles/12/2517/2020/essd-12-25...

katangafor 2y ago

Does burying wood actually work? I'm assuming it's a little more complicated than literally burying it, cause wouldn't it decay and release carbon at some point anyway?

devilbunny 2y ago
Without oxygen, any decay is going to be incredibly slow. They're still pulling usable timber from trees that sank in rivers after being cut in the southeastern US 200 years ago. It's not cheap, but if you want some real old-growth oak, it's a viable source. And that's not a completely anaerobic environment.
- williamdclt 2y ago
  200y is not really an incredibly long time at all
  - devilbunny 2y ago
    No, it's not, but that's without any noticeable decay. A tree that's been felled in that environment and left above ground will rot very quickly.
Arrath 2y ago
As most of the heavy construction and earth moving equipment you'd use to bury the wood will be burning diesel and releasing carbon the entire time, you enter some new Tyranny of the Rocket/Wagon equation.

ericd 2y ago

There's a simple way to think about this that doesn't require doing a ton of research and number crunching. Think about the volume of fuel in a single airplane, about 7,000 gallons for a 737, or about 100 55 gallon drums. It's nowhere near exact, but you can roughly equate that volume of fuel to the volume of volume of wood to compare carbon - I'm pretty sure this is being very generous to the energy density of the wood, but it gives you an upper limit on what the wood could be sequestering (I think in reality jet fuel is something like 2-3x as energy/carbon dense per m^3). Now think about how many planes take off every day from an airport, and the volume of n*100 drums. It's just nowhere near in reality, and we're not going to make a large dent via sequestration, the "finite" airports is functionally infinite for our purposes. We have to start making carbon neutral fuel. That said, manufacturing concrete is incredibly carbon intensive, so avoiding making the amount we would've needed for this building is a pretty good win.

burkaman 2y ago

> If were to bury the equivalent amount of wood, we would be equal. Burying wood that would have taken decades to decay is not equal to instantly releasing the equivalent amount of carbon. I'm not sure it's physically possible to remove CO2 from the atmosphere at the same rate a plane emits it, which would be the only way to genuinely "offset" the emissions.

closewith 2y ago

1 kilo of wood sequesters (temporarily for the most part) about 2kg CO2 equivalent, so for the GP's example of a single seat one-way from Boston - NYC, you'd need to sequester 350kg of wood. To sequester the ~800 Mt of CO2 emitted by aviation annually, you'd need to sequester about 400 billion kilograms of wood. So a finite but absurd amount.

LargeWu 2y ago
Not only that, you have to build new wooden airports every single year to keep up.
kjkjadksj 2y ago
Or you transition the airline industry to biofuels that are inherently carbon neutral.

pmayrgundter 2y ago

Interesting point! It looks like Skanska is GC for the Project, and cites it as a 9 acre (!) lumber roofing system[SK], and that it uses 3.5M board foot of Douglas Fir Project Lumber[PL]. Douglas Fir is 3.2 pounds per board foot, or 1.45kg [DFM]. So 1.45 * 3.5M = 5Mkg of lumber for PDX airport. DF has an Embodied CO2 of 1.6kgCO2/kgLumber [DFC]. A little hard to believe? But maybe that's bc a lot of the mass of a tree is left in the ground. Worth following up. 1.6kgCO2/kgLumber * 5MkgLumber = 8MkgCO2 = 8KtCO2 embodiment/sequestration from the PDX roof project. (tho there's a lot more to the project that probably goes in the other direction) Global CO2 emissions from commercial flights is ~60MtCO2/month [CF], so we need roughly 12,000 airports per month, 144,000/yr, to offset flight CO2 emissions. There's 9000 commercial airline airports [NA] (tho obv many smaller than PDX, but they would also represent less CO2 from their flights), so 144,000/9000 is a 16x annual airport rebuild rate we'd need to offset CO2 emissions from the flights they service. So yeah, this is absurd on the face of it. But, how much of the mass of an airport is the roof? If it's like 1/100th the total mass, and you start building airports with all wood (foundation, runways, etc) you'd get to 16% annual rebuild rate to offset flight emissions. Still too high to be plausible. But another 10x somehow and you get to ~1% range of annual airport rebuild rate to offset emissions. Then you'd have something. [SK] https://www.usa.skanska.com/what-we-deliver/projects/278172/Portland-International-Airport-PDX-Terminal-Core-Redevelopment https://www.usa.skanska.com/what-we-deliver/projects/278172/... [PL] https://www.forbes.com/sites/johnoseid/2024/08/19/portlands-pdx-airport-dazzles-with-its-new-timber-roof-terminal/ https://www.forbes.com/sites/johnoseid/2024/08/19/portlands-... [DFM] https://www.globalwood.org/tech/tech_wood_weights.htm https://www.globalwood.org/tech/tech_wood_weights.htm [DFC] https://www.douglasfir.co.nz/net/environment/carbon-footprint.aspx https://www.douglasfir.co.nz/net/environment/carbon-footprin... [CF] https://www.statista.com/statistics/1500409/global-aviation-co2-emissions-by-month https://www.statista.com/statistics/1500409/global-aviation-... [NA] https://sentinel-aviation.com/blog/over-40000-airports-in-the-world-only-9000-served-by-commercial-airlines https://sentinel-aviation.com/blog/over-40000-airports-in-th...

pmayrgundter 2y ago
Based on the discussion in the descendent thread with morsch, it seems like the runways are the real story, at 1000x the mass of the airport roof. But concrete is not so CO2 intensive. Lumber has a +1.6 sequestration factor of CO2 emitted vs built mass, compared with concrete at -0.8. So we'd need runways made mostly of wood, or combined with a Woodcrete that was net sequestering, and then maybe there's a way to make even our most CO2 intensive industries net neutral so long as we rebuild continuously. Also, since construction is about 40% of global CO2 emissions, if it could become a net sequestration as a whole, maybe it could flip the sign to -40% and offset most of the rest of our industrial emissions. This also got me interested in what's a good number for rebuild rate. Found a study that concludes the "Apparent ecosystem carbon turnover time [T]" is 43±7 years. So maybe we should be rebuilding our built environment at 2.3%, or probably higher since species have evolved to be more energy intensive, humans especially. [T] https://essd.copernicus.org/articles/12/2517/2020/essd-12-2517-2020.pdf https://essd.copernicus.org/articles/12/2517/2020/essd-12-25...